1. Field of the Invention
This invention relates to gate valves, and particularly to gate valves which are intended to function in a lie-down or substantially horizontal position in which the gate of the valve extends in a substantially horizontal plane.
2. Brief Description of the Problem Solved by the Invention
With some types of gate valves used in oil field service, the valve is usually employed in a lie-down or horizontally extending position in which the fluid flows through the valve in a generally vertical direction, and the gate of the valve extends in a substantially horizontal plane. In this mode of operation, some difficulty is experienced at times in maintaining an efficient seal between the seats of the valve and the gate, particularly when the gate is in an open position. Such tendency toward inadequacy of sealing capability is due in part to gravitational action on the gate and upstream seat of the valve tending to allow them to drift or move away from the downstream seat.